Detection and Estimation of Other Elements Using Phosphorus Compounds

10 Detection and Estimation of Other Elements Using Phosphorus Compounds 

Phosphate Beads. If a small quantity of microcosmic salt (Chapter 3.2) is heated on a loop of platinum wire, it fuses and forms sodium metaphosphate glass (14.12). The molten glass will react with trace metal ions, if present, to form coloured glass beads of double orthophosphates, for example, (14.13) and (14.14) (Table 14.2). 

The formation of coloured glass beads as in Equations 14.13 and 14.14 constitutes a simple method of detecting certain metal elements (this test is useful when done in parallel with a borax bead test). 

Silver. The formation of a yellow precipitate of Ag3P04 as in Equation 14.3 is a useful confirmatory test for Ag+. The precipitate is soluble in nitric acid or ammonia. 

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